Field of Technology
This application relates generally to spinal fixation. More specifically, this application is directed to a spinal plate with compression locking and a method of fixating vertebrae using the spinal plate with compression locking.
Brief Description of Related Art
Spinal surgery frequently requires fixation of the spinal column, e.g., spinal fixation of a plurality of spinal vertebrae. Spinal vertebrae are bony cylindrical structures that are located in front of the spinal cord and nerves; they contribute to the structural support of the axial skeleton. Anterior or lateral spinal fixation can be used to fixate vertebrae along the cervical, thoracic and lumbar regions of the spinal column.
Generally, a spinal plate and a plurality of screws are used for spinal fixation. The spinal plate is placed over multiple vertebrae to be fixated with respect to one another. Generally, the openings through the spinal plate have matching geometry to the screws, allowing screw angulations over a range of trajectories through the spinal plate. The screws anchor the spinal plate to the vertebrae. The screw angulations provide for various screw placements given different anatomy of patients and locations along the spinal column.
Screw back-out that results from the loosing of the screws with respect to the spinal plate is a significant concern. When screws loosen, their screw heads pivot about the openings of the spinal plate with spinal plate motion in respect to the vertebrae. Unrestricted movement can result in screw dislodgement with respect to the spinal plate, jeopardizing the patient's health.
Multiple back-out mechanisms have been proposed. However, the back-out mechanisms do not adequately lock (rigidly fixate) the screws (via their screw heads) in their trajectories with respect to the spinal plate, but rather attempt to prevent dislodgement of the screws from the spinal plate. For rigid fixation versus back-out prevention, the potential for pivoting of screw heads about the openings in the spinal plate should be restrained.
Furthermore, the foregoing back-out mechanisms usually include multiple components that require complex engagement with respect to the spinal plate and screws, blocking visualization of the underlying vertebra and increasing undesirably the size of the spinal plate.